Sauceda Gamboa appears on a list of 24 alleged drug traffickers published by prosecutors in March. Authorities have offered rewards of up to $2.1 million for each suspect. Together with a list of 13 lower-ranking drug suspects, the group covers Mexico's most powerful cartel operators.

With Sauceda Gamboa's arrest at a home in Matamoros, across the border from Brownsville, Texas, authorities have arrested five of the 37 people on the lists.

Sauceda Gamboa, 44, was a former investigative police officer who played a founding role in the Gulf cartel starting in 1996, federal police said.

“Because of his violent character, he was assigned . . . to fight off the (rival) Pacific cartel,” said Gen. Javier del Real Magallanes, a top federal police intelligence official.

Federal police said the raid on the home was the result of intelligence work and tips.

In a reflection of the swine flu epidemic sweeping Mexico, Sauceda Gamboa was wearing a surgical mask as he was paraded before reporters by police, who also were wearing the masks in addition to the black ski masks they normally use to hide their identities.

Authorities said yesterday they also seized five rifles and more than 4,500 rounds of ammunition in the raid, and detained a woman believed to be Sauceda Gamboa's wife, along with another man.

Sauceda Gamboa helped the Gulf cartel move an average of 10 tons of cocaine and 30 tons of marijuana across the border each month, and briefly headed the gang, police said, although they acknowledged his personal involvement in the operation had declined in recent years.